Technique: iMac Intel 20" EMC 2210 Power Supply Output Voltage Test

Member-Contributed Guide

Member-Contributed Guide

An awesome member of our community made this guide. It is not managed by iFixit staff.

  • Author: Richdave
  • Time required: 30 minutes
  • Difficulty: Difficult

* The purpose of this guide is to provide detail on testing of the iMac PSU voltages.

  • Should only be attempted by those with experience working with a multimeter or voltmeter and LIVE equipment.
  • If you don't know how to use a meter to measure voltages then you should not proceed.

Edit Step 1 Access Door  ¶ 

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Edit Step 1 Access Door  ¶ 

  • Loosen the single Phillips screw in the center of the access door.

  • This screw is captive in the access door.

  • Remove the access door from your iMac.

Edit Step 2 Glass Panel  ¶ 

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Edit Step 2 Glass Panel  ¶ 

  • The glass panel is fixed onto the front bezel with fourteen magnets around its perimeter.

  • Stick two suction cups to opposing corners of the glass panel.

  • To attach the suction cups we sell, first position the suction cup with the movable handle parallel to the face of the glass panel. While lightly holding the suction cup against the glass, raise the movable handle until it is parallel with the other handle.

  • If your suction cups refuse to stick, try cleaning both the glass panel and the suction cup with a mild solvent such as Windex.

Edit Step 3  ¶ 

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Edit Step 3  ¶ 

  • Gently pull the glass panel straight up off the iMac.

  • The glass panel has several positioning pins around its perimeter. To avoid shearing these pins off the glass panel, be sure to only pull straight up during removal.

  • Be meticulous about cleaning the LCD and the inside face of the glass panel before reinstallation, as any fingerprints or dust trapped inside will be annoyingly visible when the display is on. Placing the glass flat, inside face down, on a fresh aluminum-foil surface is a good way to keep it clean.

Edit Step 4 Front Bezel  ¶ 

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Edit Step 4 Front Bezel  ¶ 

  • Remove the following 12 screws securing the front bezel to the rear case:

    • Eight 13 mm T8 Torx.

    • Four 25 mm T8 Torx.

Edit Step 5  ¶ 

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Edit Step 5  ¶ 

  • Disconnect the microphone cable connector, removing tape as necessary.

  • For the front bezel to sit properly, be sure to tuck the microphone cable and connector into the void next to the camera board.

Edit Step 6 iMac Intel 20" EMC 2210 Power Supply Output Voltage Test  ¶ 

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Edit Step 6 iMac Intel 20" EMC 2210 Power Supply Output Voltage Test  ¶ 

  • After removing the front bezel, you need to remove the 8ea 12mm T8 screws around the perimeter of the LCD

  • Rotate the iMac so the TOP EDGE is facing you and GENTLY lift the LCD up about 75mm (3in) and prop up the LCD with something NON CONDUCTIVE.

  • Lifting the LCD in this way exposes the rear of the PSU to allow access to the PSU connector. When the imac is connected to the mains (even if switched OFF) there is MAINS VOLTAGE on this board

Edit Step 7  ¶ 

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Edit Step 7  ¶ 

  • REMEMBER - there is MAINS voltage on the PSU so use extreme caution

  • Use the chart provided as a reference and test the various voltages with your meter being sure to restrict the probes to the 10 solder joints on the PSU connector shown within the BLUE rectangle. Shorting any part of the PCB will almost certainly cause damage to the imac

  • All voltage measurements are taken with PIN 1 as reference (Marked with the YELLOW square). Pin 1 is marked on the board by a dot and is the right hand pin when viewed as shown in photos

  • STANDBY means system connected to mains outlet but imac turned off - Diagnostic LED 1 will be illuminated on logic board

  • Pin 5 is the PSU enable line - Logic board pulls this line low (0V) to enable PSU (probably via a resistor)

  • Pin 4 voltage varies according to the PSU temperature and is inversely proportional to PSU temperature. Higher Temp = Lower Voltage. My measurement was taken at around **24 Deg Celsius.

  • Reassemble your iMac in reverse order. When lowering the LCD ensure you don't crimp or crush the LCD back-light cables

To reassemble your device, follow these instructions in reverse order.

For more information, check out the iMac Intel 20" EMC 2133 and 2210 device page.

Required Tools

Heavy-Duty Suction Cups (Pair)

$14.95 · 50+ In stock

Digital Multimeter

$19.95 · 50+ In stock

Phillips #1 Screwdriver

$5.95 · 50+ In stock

TR8 Torx Security Screwdriver

$4.95 · 50+ In stock

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Comments Comments are onturn off

isn't it actually pc2-5300s ?

grze, · Reply

At this stage and later handling the LCD I found thin cotton gloves helped to reduce smudges

john31, · Reply

My GPS unit's car mount suction cup worked nicely here - couldn't find any at the store and didn't want to wait for mail order!

Two cups would make it easier but one is fine if you place it in the center and are careful to pull the panel straight out.

Mathew Hendry, · Reply

Why use suction cups when some finger nails will do the job nicely, though a plastic spudger might work too. Start at a top corner. Prize the glass away from the case and leave finger nails in. Move the other hand along the top edge and then with finger spread peel the screen cover away. Be careful not to twist plastic I suppose, but I've had no difficulties.

damianwise, · Reply

3M Command Strip hooks in opposite corners is another fabulous option when suction cups are not available!

Adam McCombs, · Reply

Tape works fine, here. Search for a YouTube video for a simple look-see.

Richard, · Reply

I didn't have any suction cups, but my pencil sharpener (the kind that suctions to the table) worked great. I put it on the middle and lifted straight up.

Lisa Mac, · Reply

For a quick 'n' dirty alternative "tool" for this step, take a look at IKEA's Stugvik suction hooks: they provide an excellent adjustable grip. Just used it to take apart an EMC2133. Cheers!

hadderakk, · Reply

In order to avoid unnecessary smudges and what not I covered the LCD itself with some plastic wrap while doing the hard drive upgrade. When I reinstalled it all I needed to do was blow off a few dust particles.

robgendreau, · Reply

While you are at it, it is worth cleaning out dust within the case to help with cooling - particularly around the fans and vents.

For the screen I used a lens cleaner from my camera bag. These have very fine fibers and won't leave detritus.

Mathew Hendry, · Reply

Note that the front glass panel is quite light. When reassembling I found it impossible to get the LCD free of dust with the computer lying on its back. I had success with standing the computer up, tilting the LCD down as far as it goes, holding the glass panel upright in front of the computer (about 1 foot away), lightly spraying both the LCD and the back side of the glass panel with compressed air, and then attaching the glass panel (with the computer upright). It took me 5 tries before it was completely clean of dust once the front glass was on.

axel, · Reply

On the 24" EMC2134 there are 3 screw sizes: 6x13, 4x20 & 2x30mm, particular note should be made of their location.

john31, · Reply

Note for the less experienced.. the case is plastic and the metal coarse thread screws will easily cut a new thread in the hole if you don't line up the screw in the original thread. Do this a few times and the hole will be stripped and the screw no longer tightens.

TIP:- place the screw in the hole and rotate BACKWARDS/counter clockwise (for RH threads) until you hear/feel it click/drop into the original thread then tighten the screw down. rotate it a couple times to get the feel of things. If there is any significant resistance you probably don't have the original thread.

This trick also works on the fine metal thread screws and can help avoid cross threading them.

HIH

Richdave, · Reply

On the 24 inch iMac Model A1225 EMC #2134, the two T8 Torx screws in the middle are the longer of the four total bottom 25 mm screws. Just a note for reassembly.

bhoffs, · Reply

I avoided this step by just flipping the housing over and having it lay flat on the table. The tape on mine was on really tight, and I risking ripping the wires out of the connector if I messed with it (I didn't have some really small scissors which might have helped removing it). I would suggest either securing the body of the iMac and the housing to the table you're working on, or somehow securing the housing to the body, so that it doesn't move around accidentally, since it's only hanging on by a very thin wire at that point.

robgendreau, · Reply

Make sure you do not pull this apart by the wires. Have a firm grasp on the plastic parts. Do not force back together. It only goes back together one way. Also, it is crucial when placing the aluminum bezel back in place that this wire is out of the way. It often gets in the way and is easily damaged.

Kyle Freeman, · Reply

CAUTION - To disconnect the cable, you'll need to support the bezel while you carefully extract slack microphone cable which is tightly tucked within the iMac. (I didn't have this guide's 'notes on' and missed robgendreau's warning - then inadvertently shifted the bezel and busted my microphone cable in this step.)

dagnew, · Reply

Don't forget to pull the microphone cord out before you put the panel back on. Otherwise you will have to go back and remove screws to find that microphone cord

Melvin Hines, · Reply

As robgendreau says, avoid this whole step by opening the bezel and laying it upside down above the iMac, still connected by the mic cord, just carefully. Then replace the battery, suck/blow out your dust, and carefully rotate the front bezel back over the iMac from where you removed it. No cord manipulation or damage at all!

recmsoj, · Reply

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